The Undine are a race similar to the Sirens, save a few key differences, the most obvious being that they do not shapeshift nor lose their voices on land. Their upper body is that of a beautiful human woman, similar to the siren's. Their lower body is that of a great serpent with traits of a fish, such as fins that help them swim and a prominent dorsal fin, located near the pelvis. The positioning and nature of these fins vary between individuals and help with identification, but do not interfere with snake-like locomotion on dry land. They also usually have noticeably inhuman traits to their faces, such as fin-like projections where their ears should be, forked tongues, and some elongated, fang-like teeth.

Undine are extremely swift swimmers but are much slower on land, and a fit human can usually outrun them. That said, their tails are very powerful and they can lunge with surprising speed.

Undine lack many of the supernatural tricks of the Sirens and while they do have musical voices and love to sing, they cannot actually charm people. The magic of their voice is instead of a physical sort, and some Undine can produce a shriek powerful enough to cause physical damage. A sustained blast can even prove fatal. The "corruption" of their body and voice has lead to a popular belief that they are the descendants of sirens who somehow fell from grace and lost the ocean's blessing, and it is generally accepted that the two races are somehow related.

Culture

Undine do not live in Rebma, and refused to join the Concordance out of fear that it would lead to a loss of their culture or worse, that they would lose their identity to the Sirens, whom they consider to be dishonest and manipulative. This disagreement has become cultural; Undine do not like Rebmans and Rebmans do not like Undine, doubly so for Sirens. Instead, they live in nomadic tribes, often inhabiting places inhospitable to Rebmans, as they can dive much deeper and much longer than their neighbors and recover quickly from even severe injuries. While Rebman royalty claims dominion over all within Rebman waters, Undine beg to differ. They are not open traitors to the crown but they disagree that it has any jurisdiction over them.

Theirs is a race of females and do not bear males at all, unlike the Sirens who sometimes birth a male of the father's race. They bear live, and only rarely more than one child at once. When they wish to increase their number, they sometimes approach or attack ships for their men. What the Undine does with the male when she's done with him depends on the individual, but legends say she will kill him or leave him to die. Tribes are as families, and all members participate in the rearing of all children. Other than for purposes of reproduction or the rare bit of trade, tribes keep to themselves and while not considered openly hostile, they are far from friendly to outsiders. They prefer evasion to conflict. When they do trade, they usually provide little trinkets or salvage from wrecks that only they can reach.

Given their reclusive nature, most Rebmans have never seen an Undine. While one occasionally does leave the oceans to live among other races, this is extremely unusual, and she will usually seek a settlement in another shadow rather than live with fellow Rebmans. Integration can be difficult and traumatic for the Undine and for her new hosts, and only rarely can she become more than a second-class citizen.

Common Beliefs

- Undine are violent. Most sailors, particularly those from Minos, see them as aggressive raiders, murderers, and even rapists. While the reputation is not entirely undeserved, most tribal Undine will not attack without reason. Those who have left their tribes usually make an effort to stay out of trouble.

- Undine are Sirens. While they look close enough to a layman, they have very little patience for this mistake. They also resent being called "cursed," a common belief of uncertain truth.

- Undine are monsters. To those who have never heard of an Undine or a Siren, they are simply monsters, and monsters are dangerous animals with no rights. Truth be told, they'd rather be confused for a Siren.

- Undine can charm men. This rumor has been kept alive by men with wandering eyes and angry wives. Despite their lovely singing voice, they have no more power over a man than any other beautiful woman.

- Undine are venomous. Between their sharp teeth and snake-like appearance, some people believe their bite delivers a deadly poison. Undine do little to discourage this myth.